ESP32 SHT35 Temperature and Humidity Sensor

Code Examples

Below you can find code examples of SHT35 Temperature and Humidity Sensor with ESP32 in several frameworks:

• Arduino IDE
• ESP-IDF
• ESPHome
• PlatformIO
• MicroPython

If you encounter issues while using the SHT35 Temperature and Humidity Sensor, check the Common Issues Troubleshooting Guide.

ESP32 SHT35 Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the SHT35 Temperature and Humidity Sensor:

#include <Wire.h>
#include "Adafruit_SHT31.h"

Adafruit_SHT31 sht31 = Adafruit_SHT31();

void setup() {
  Serial.begin(115200);
  while (!Serial) delay(10);

  if (!sht31.begin(0x44)) {   // Set to 0x45 for alternate I2C address
    Serial.println("Couldn't find SHT35");
    while (1) delay(1);
  }
}

void loop() {
  float t = sht31.readTemperature();
  float h = sht31.readHumidity();

  if (!isnan(t) && !isnan(h)) {  // check if 'is not a number'
    Serial.print("Temp *C = "); Serial.print(t); Serial.print("	");
    Serial.print("Hum. % = "); Serial.println(h);
  } else {
    Serial.println("Failed to read from SHT35 sensor");
  }

  delay(1000);
}

This Arduino sketch demonstrates how to interface with the SHT35 sensor using the Adafruit SHT31 library. It initializes the sensor and reads temperature and humidity data every second, printing the results to the Serial Monitor. The sensor's I2C address is set to 0x44 by default; if your sensor uses the alternate address (0x45), adjust the initialization accordingly.

Connect your ESP32 to your computer via a USB cable, Ensure the correct Board and Port are selected under Tools, Click the "Upload" button in the Arduino IDE to compile and upload the code to your ESP32.

ESP32 SHT35 ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the SHT35 Temperature and Humidity Sensor, here's how you can set it up and read data from the sensor. Fill in this code in the main ESP-IDF file:

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2c.h"

#define I2C_MASTER_SCL_IO    22    /*!< GPIO number used for I2C master clock */
#define I2C_MASTER_SDA_IO    21    /*!< GPIO number used for I2C master data */
#define I2C_MASTER_NUM       I2C_NUM_0 /*!< I2C master I2C port number */
#define I2C_MASTER_FREQ_HZ   100000     /*!< I2C master clock frequency */
#define SHT35_SENSOR_ADDR    0x44       /*!< SHT35 I2C address */

static esp_err_t i2c_master_init(void) {
    i2c_config_t conf = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = I2C_MASTER_SDA_IO,
        .scl_io_num = I2C_MASTER_SCL_IO,
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
        .master.clk_speed = I2C_MASTER_FREQ_HZ,
    };
    esp_err_t err = i2c_param_config(I2C_MASTER_NUM, &conf);
    if (err != ESP_OK) {
        return err;
    }
    return i2c_driver_install(I2C_MASTER_NUM, conf.mode, 0, 0, 0);
}

void read_sht35_sensor() {
    uint8_t data[6];
    i2c_master_write_read_device(I2C_MASTER_NUM, SHT35_SENSOR_ADDR, NULL, 0, data, sizeof(data), pdMS_TO_TICKS(1000));

    uint16_t temp_raw = (data[0] << 8) | data[1];
    uint16_t hum_raw = (data[3] << 8) | data[4];

    float temperature = -45 + 175 * ((float)temp_raw / 65535.0);
    float humidity = 100 * ((float)hum_raw / 65535.0);

    printf("Temperature: %.2f °C, Humidity: %.2f %%\n", temperature, humidity);
}

void app_main() {
    ESP_ERROR_CHECK(i2c_master_init());

    while (1) {
        read_sht35_sensor();
        vTaskDelay(pdMS_TO_TICKS(2000));
    }
}

This ESP-IDF code demonstrates how to interface with the SHT35 sensor using the I2C interface. The I2C master is initialized on GPIO21 (SDA) and GPIO22 (SCL). The `read_sht35_sensor()` function reads raw temperature and humidity data from the SHT35 sensor and converts it into human-readable values. These values are printed to the console every 2 seconds.

Update the I2C pins (I2C_MASTER_SDA_IO and I2C_MASTER_SCL_IO) to match your ESP32 hardware setup, Use idf.py build to compile the project, Use idf.py flash to upload the code to your ESP32.

ESP32 SHT35 ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the SHT35 Temperature and Humidity Sensor

sensor:
  - platform: sht3x
    address: 0x44
    temperature:
      name: "Living Room Temperature"
    humidity:
      name: "Living Room Humidity"
    update_interval: 60s

This ESPHome configuration defines the SHT35 sensor using the `sht3x` platform. The I2C address is set to 0x44 (default for the sensor). Two entities are configured: one for temperature and one for humidity, with descriptive names like 'Living Room Temperature' and 'Living Room Humidity.' The `update_interval` is set to 60 seconds, meaning the data will be updated every minute.

Upload this code to your ESP32 using the ESPHome dashboard or the esphome run command.

ESP32 SHT35 PlatformIO Code Example

Example in PlatformIO Framework

For PlatformIO, make sure to configure the platformio.ini file with the appropriate environment and libraries, and then proceed with the code.

Configure platformio.ini

First, your platformio.ini should look like below. You might need to include some libraries as shown. Make sure to change the board to your ESP32:

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
lib_deps = 
    adafruit/Adafruit SHT31 Library @ ^1.2.0
monitor_speed = 115200

ESP32 SHT35 PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the SHT35 Temperature and Humidity Sensor:

#include <Wire.h>
#include "Adafruit_SHT31.h"

Adafruit_SHT31 sht35 = Adafruit_SHT31();

void setup() {
    Serial.begin(115200);
    while (!Serial) delay(10);

    if (!sht35.begin(0x44)) {   // Default I2C address for SHT35
        Serial.println("Couldn't find SHT35 sensor!");
        while (1) delay(1);
    }
}

void loop() {
    float temperature = sht35.readTemperature();
    float humidity = sht35.readHumidity();

    if (!isnan(temperature) && !isnan(humidity)) {  // Check if readings are valid
        Serial.print("Temperature: ");
        Serial.print(temperature);
        Serial.println(" °C");
        Serial.print("Humidity: ");
        Serial.print(humidity);
        Serial.println(" %");
    } else {
        Serial.println("Failed to read from SHT35 sensor!");
    }

    delay(2000);  // Wait 2 seconds between readings
}

This PlatformIO sketch demonstrates how to interface with the SHT35 sensor using the Adafruit SHT31 library. The sensor is initialized on its default I2C address (0x44). Temperature and humidity values are read every 2 seconds and printed to the Serial Monitor. If readings fail, an error message is displayed.

Upload the code to your ESP32 using the PlatformIO "Upload" button in your IDE or the pio run --target upload command.

ESP32 SHT35 MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the SHT35 Temperature and Humidity Sensor with your ESP32.

from machine import I2C, Pin
import time

# SHT35 default I2C address
SHT35_I2C_ADDRESS = 0x44

# Initialize I2C communication (SDA=21, SCL=22)
i2c = I2C(0, scl=Pin(22), sda=Pin(21))

def read_sht35():
    # Send measurement command (high repeatability, no clock stretching)
    i2c.writeto(SHT35_I2C_ADDRESS, b'\x24\x00')
    time.sleep(0.015)  # Wait for measurement to complete

    # Read 6 bytes of data
    data = i2c.readfrom(SHT35_I2C_ADDRESS, 6)

    # Convert the data
    temp_raw = (data[0] << 8) | data[1]
    humidity_raw = (data[3] << 8) | data[4]

    # Calculate temperature and humidity
    temperature = -45 + (175 * temp_raw / 65535.0)
    humidity = 100 * humidity_raw / 65535.0

    return temperature, humidity

while True:
    try:
        temperature, humidity = read_sht35()
        print("Temperature: {:.2f} °C".format(temperature))
        print("Humidity: {:.2f} %".format(humidity))
    except Exception as e:
        print("Failed to read from SHT35 sensor:", e)

    time.sleep(2)

This MicroPython script interfaces with the SHT35 sensor using the I2C protocol. The `read_sht35` function sends a command to the sensor to initiate a measurement, waits for the response, and then reads 6 bytes of data. The raw data is processed into human-readable temperature (°C) and humidity (%) values. The script continuously reads and prints these values every 2 seconds. Error handling is included to manage failed readings.

Upload this code to your ESP32 using a MicroPython-compatible IDE, such as Thonny, uPyCraft, or tools like ampy.